1. Field of the Invention
This invention relates generally to a method of producing a weather strip having a metal core, and more particularly to a method of producing a weather strip that a decorating treatment and/or a lubricating treatment are applied onto a surface of a rubber base made of EPDM (ethylene-propylene-diene copolymer rubber).
2. Related Art
Conventionally, a glass run serving as a weather strip is provided, for example, between a door sash and a window pane of glass in an automobile. Generally, the glass run is formed by EPDM (ethylene-propylene-diene copolymer rubber). In order to enhance sliding properties, a coating of a lubricant, such as silicone and urethane paint, or a flock has been applied to those portions of the glass run disposed in sliding contact with the window pane, and also a non-metallic glass slide-promoting member, such as a sheet made of polyester and a cloth, has been bonded to the sliding-contact portions of the glass run.
Further, for example, in an automobile, a door opening trim (hereinafter referred to as "D.O. trim"), serving as a weather strip for sealing a gap between a body and a door, has been mounted on a peripheral edge portion of a door opening in the automobile body. Generally, this D.O. trim is also formed by EPDM, and prevents rain water, dust, noises and others from intruding into a passenger room of the automobile. EPDM forming the glass run and the D.O. trim is a material having a black color, and hence is unappealing in design. Therefore, a decorative member (e.g. cloth) of a color matching the color tone in the passenger room has heretofore been bonded to a surface of the rubber base.
However, the above-mentioned EPDM contains few if may polar functional groups, and therefore if it is bonded merely by an adhesive, sufficient bonding strength can not be obtained. Therefore, when a glass slide-promoting member is bonded to a surface of the rubber base of the glass run by an adhesive, or a decorative member to the surface of the rubber base of the D.O. trim by an adhesive, the following bonding method has heretofore been adopted. First, a buffing treatment is applied for roughening a surface of the rubber base which has been extruded and vulcanized. Thereafter, the steps of degreasing, coating of a primer, coating of an adhesive, drying, bonding of the above-mentioned glass slide-promoting member and decorative member, and curing of the adhesive are performed. With these sequential treatments, the glass slide-promoting member, the decorative member or the like is bonded to the surface of the rubber base.
According to the above conventional bonding technique, the mentioned treatments must be applied after the vulcanization treatment. This results in a long production line, which results in low productivity and increased costs. Further, dust is produced during the buffing treatment, so that there may be a potential for worsening the work environment. Typical of these art processes are those shown in GB2127713A and Japanese Patent Unexamined Publication No. 3-253331.